Pump



1950 s. R. F. VANDERSTEGEN-DRAKE 2,

PUMP

. Filed Dec. 9, 1958 I n venlor STAMFORD ROBERT FRANCE VANDERSTEGEN'DRAKE United States Patent chinswell, Newbury, England, assignor to Plenty and Son Limited, Newbury, England Filed Dec. 9, 1958, Ser. No. 779,087

5 Claims. (Cl. 103-120) This invention relates to variable-capacity pumps.

,In a number of British patents, for example, British Patent No. 740,934, there is described a variable-capacity pump of the sliding vane type comprising a casing having a fiat-sided rectangular sliding block provided with a cylindrical recess in which a rotor is rotatably supported. The rotor has a number of inwardly-facing bearing surfaces which are in bearing engagement with the ends of vanes slidingly mounted in slots formed in a rotor shaft passing through the rotor. The rotor shaft is mounted in bearings arranged in bearing housings fixed to or forming part of the casing so that vertical displacement of the sliding block causes the rotor and the rotor shaft to be moved relatively to each other--thus varying the capacity ofthe pump. This type of pump gives very good results, but its manufacture is not a simple matter. One reason for this is that the fiat faces of the rectangular sliding block must make a close sliding fit with the corresponding faces onthe casing, and this entails a difiicult slotting operation followed by a skilled fitting operation. In addition, the housings for the bearings which support the rotor shaft are usually mounted on cover plates which are fitted on the pump casing, and those cover plates have to be carefully located on the casing by skilled workmen.

The main aim of the present invention is to provide a pump of the same basic construction as that described above but which is more simple to manufacture.

According to the invention, a variable-capacity rotary pump has a rotor and a rotor shaft which can be displaced relatively to each other so as to vary the capacity of the pump, in which the rotor or the rotor shaft is carried by a sliding block of part-cylindrical shape having a pair of flat parallel faces one on either side of its longitudinal axis, the sliding block being arranged for sliding movement in a cylindrical bore or aperture in the pump casing.

Preferably, the cylindrical bore in the casing is intersected at 90 by a second cylindrical bore which receives the rotor shaft and serves also to locate and support the housings for the shaft bearings, the housings having cylindrical portions for this purpose which fit accurately into the second bore.

The advantages of this construction from the manufacturing standpoint are quite considerable, and these advantages will be indicated in the following description of a specific pump in accordance with the invention which is shown, by way of example, in the accompanying drawing, in which:

Figure 1 is a vertical section through the pump; and

Figure 2 is a section taken on the line Il-II in Figure 1.

The pump shown in the drawing comprises a casing having a vertical cylindrical bore 12, a horizontal cylindrical bore 14, and another horizontal cylindrical bore 16. These three bores pass through each other within the casing, and their respective axes AA, BB and CC intersect at a single point 18 and at 90 to each other.

The vertical bore 12 is closed at its top by a cover which supports an internally screw-threaded control wheel 22. The control wheel 22 is held against vertical movement by a nut 24 having a locking screw 26, and is threaded on a rod 28 which is screw-threaded at its lower end into a sliding block 30 arranged for vertical sliding movement within the bore 12. The sliding block 30 is of part-cylindrical shape in that its cylindrical surface 32 (see Figure 2) is broken by a pair of flat parallel surfaces 34 provided one on either side of its longitudinal axis. Arranged for rotation in the sliding block 30 is a rotor 36 having fiat internal surfaces 38 which are in bearing engagement with the ends of vanes 40 slidingly mounted in slots formed in a rotor shaft 42 passing through the rotor 36. Variation in the capacity of the pump is achieved by rotating the control wheel 22 which causes the sliding block 30 to be raised or lowered, thus altering the relative positions of the rotor 36 and the rotor shaft 42.

The horizontal bore 14 receives the rotor shaft 42 and housings 44 and 46 for bearings 48 and 50 which sup port the shaft. It will be seen that the housings 44 and 46 have cylindrical outer surfaces which allow the hous ings to be fitted accurately into the bore 14. The ends of the bore 14 are closed by cover plates 52 and 54.

The other horizontal bore 16 forms the suction and delivery passages to and from the rotor 36, and extends right through the casing 10.

One of the main advantages of the pump described above is that the casing 10 is easier to construct as the machining of the three intersecting bores 12, 14 and 16 does not present any real difiiculty. The part-cylindrical sliding block 30 can also be made more easily than the flat-sided rectangular block used hitherto and does not have to be fitted in the casing 10 during assemblyby skilled workmen. Furthermore, the bore 14 in thecasing which receives the rotor shaft 42 serves to align the bearing housings 48 and 50 accurately in the casingagain without the need of skilled labour.

Quite apart from the replacement of skilled labour by unskilled labour during assembly of the pump, it is to be noted that most of the machining operations can be carried out on lathes, and the use of other more expensive machinery is obviated.

A pump in accordance with the invention can be constructed in the following manner.

The pump casing is bored so as to provide a vertical bore and two horizontal bores, one larger than the other, intersecting in the centre of the casing at to each other. The sliding block is produced from a cylinder by machining a pair of flat parallel faces one on either side of its longitudinal axis. A bearing housing for supporting one end of the rotor shaft is then inserted into the larger horizontal bore of the casing, after which the sliding block is lowered into the vertical bore of the casing with its fiat face lying at right angles to the axis of the larger horizontal bore. A cylindrical recess in the sliding block now receives the rotor assembly which is inserted into the casing through the larger horizontal bore, and when this has been completed a second cylindrical bearing housing for supporting the other end of the rotor shaft is moved into the end of the said horizontal bore.

It will be seen that this procedure is not difiicult, and it allows a pump of similar construction to that described for example in British Patent No. 740,934 to be manufactured more easily and at less expense.

I claim:

1. A variable-capacity rotary pump comprising a casing, a pumping chamber within said casing, a rotor shaft rotatably supported within said casing and passing through said pumping chamber, a plurality of sliding vanes projecting from said rotor shaft, a rotor surrounding said rotor shaft and engaging end surfaces of said vanes, a regularly-shaped sliding block slidably mounted within said casing and having two pairs of opposite side surfaces Patented Nov. 29, 1960 V extending from the top to the bottom of said block, said sliding block surrounding and supporting said rotor whereby sliding movement of said block causes said rotor and said rotor shaft to be displaced relatively to each other so as to vary the capacity of said pump, one pair of said opposite side surfaces on said block comprising a pair of flat parallel, vertical faces on said block formed one on each side of a vertical axis passing through the centre of said block and lying at right angles to the axis of said rotor shaft, said flat parallel faces slidably abutting flat-surfaced means closing opposite ends of said pumping chamber, said other pair of said side surfaces on said block comprising a pair of part-cylindrical faces on said block formed one on each side of said vertical axis of said block and having radii centred on said vertical axis, said part-cylindrical faces being in mating engagement with internal part-cylindrical surfaces on said casing, said part-cylindrical surfaces on said casing defining at least partially a bore in said casing for slidably supporting said sliding block.

2. A variable-capacity pump as claimed in claim 1 comprising a second cylindrical bore in said casing, housings for rotor shaft bearings located and supported within said second cylindrical bore, said second cylindrical bore intersecting said first cylindrical bore centrally of said casing at substantially 90 whereby boring of said first bore and said second bore is facilitated.

3. A variable-capacity pump as claimed in claim 1 comprising a second cylindrical bore in said casing, housings for rotor shaft bearings located and supported within said second cylindrical bore, said second cylindrical bore intersecting said first cylindrical bore centrally of said casing at substantially 90 whereby boring of said first bore and said second bore is facilitated, cylindrical portions of said housings for said rotor shaft bearings whereby said housings fit accurately into said second cylindrical bore.

4. A variable-capacity pump as claimed in claim 1 4 comprising a second cylindrical bore in said casing, housings for rotor shaft bearings located and supportedwithin said second cylindrical bore, said second cylindrical bore intersecting said first cylindrical bore centrally of said casing at substantially 90, a third cylindrical bore in said casing serving as the suction and delivery passages for fluid passing through said pump, said third cylindrical bore intersecting said first and said second cylindrical bores at substantially 90 whereby boring of said first bore, said second bore and said third bore is facilitated.

5. A variable-capacity pump as claimed in claim 1 comprising a second cylindrical bore in said casing, housings for rotor shaft bearings located and supported within said second cylindrical bore, said second cylindrical bore intersecting said first cylindrical bore centrally of said casing at substantially 90, a third cylindrical bore in said casing serving as the suction and delivery passages for fluid passing through said pump, said third cylindrical bore intersecting said first and said second cylindrical bores at substantially 90 whereby boring of said first bore, said second bore and said third bore is facilitated, the longitudinal axes of said first bore, said second bore and said third bore all intersecting at a single point within said casing, at least one of said bores passing from one side of said casing to an opposite side of said casing.

References Cited in the file of this patent UNITED STATES PATENTS 2,031,749 Vincent Feb. 25, 19 36 2,192,660 Johnson Mar. 5, 1940 2,291,424 Wichorek July 28, 1942 2,604,853 Taylor July 29, 1952 2,612,114 Ernst Sept. 30, 1952 2,804,016 Moore Aug. 27, 1957 FOREIGN PATENTS 740,934 Great Britain Nov. 23, 1955 

